Shift Accumulation

WARNING: This page is about a different car, the 2007 Pontiac G5 Pursuit, 2007 Pontiac G5, and 2007 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.

1-2 Accumulator

Second clutch fluid is also routed to the 1-2 accumulator piston. A combination of second clutch fluid pressure and the 1-2 assist spring force moves the piston against this spring force and the 1-2 accumulator feed fluid pressure. This action absorbs the initial second clutch fluid pressure in order to cushion the second clutch apply. The movement of the 1-2 accumulator piston forces some of the fluid out of the accumulator.

1-2 Accumulator Valve

The 1-2 accumulator feed fluid which is forced from the 1-2 accumulator unseats the #4 checkball. This fluid is then routed back to the 1-2 accumulator valve. This pressure forces the 1-2 accumulator valve against a combination of spring force and torque signal fluid pressure in order to regulate the exhaust of excess accumulator fluid. This regulation provides additional control for the second clutch apply.

TCC Control - Pulse Width Modulated (PWM) Solenoid Valve

Filtered 2-3 drive fluid is routed to the TCC control solenoid valve. Under normal operating conditions the TCC control solenoid valve is Off in Second gear. This valve blocks filtered 2-3 drive fluid from entering the TCC signal fluid circuit.

Torque Converter Clutch

With the TCC control solenoid valve Off, the converter clutch is released in Second gear.

2-3 Shift Solenoid Valve

The 2-3 shift solenoid valve remains Off in Second gear, and the 2-3 signal fluid exhausts through the normally open solenoid valve.

2-3 Shift Valve

A spring force keeps the 2-3 shift valve in the downshifted position. In this position the valve blocks 2-3 drive fluid, in preparation for the upshift into Third gear.